During voice telecommunication, the voice of a speaker at one end is output at the second end. The output voice is picked up by the microphone at the second end and is sent back to the speaker as an echo. In order to overcome the problem of the echo, an acoustic echo canceller is provided to estimate the acoustic echo and remove it from the signal output by the microphone. During start-up of the voice communication, the acoustic echo canceller provides rapid echo cancellation, however the rapid echo cancellation methods generally overshoot and cancel voice which is not echo. Therefore, after start-up the acoustic echo canceller enters a steady state mode where the acoustic estimation is more accurate, however response to changes is not as rapid as during the start-up.
In the event that there is a change in the acoustic echo path between the speaker and the microphone, such as when someone waves his hand in front of the microphone or speaker, the steady state of the acoustic echo canceller is unable to properly estimate the acoustic echo and the echo cancellation is less effective, causing echo on the voice communication. Therefore, an acoustic echo path change detector is provided in order to detect a change in the acoustic echo path. If a change in the acoustic echo path is detected, the acoustic echo canceller is switched to the rapid start-up mode in order to fix the acoustic echo estimation and improve the echo cancellation. Unfortunately, prior art acoustic echo path change detectors suffer from the need to trade-off between speed and accuracy of echo path change detection. As a result, fast detectors are less accurate and accurate detectors are slow. Additionally, the speed and accuracy of prior art acoustic echo path change detectors require improvement in order to improve the quality of voice communication.